As early as the 1930's, rotary dental instruments began to employ diamond abrasive to advantage over fluted cutter type instruments. With the emerging popularity of high speed turbine dental handpieces diamond instruments gained further advantage and widespread usage. While there had been some experimentation with brazing and other forms of bonding to bond diamond abrasives to rotary dental tool blanks, the overwhelming standard method was mechanical entrapment in a layer of electroplate. This process usually employed nickel but frequently included nickel in combination with other metals, such as an overplate of chromium. In 1971, Lowder, et al. discovered advantages of a hard nickel braze bond composition, described in U.S. Pat. Nos. 3,894,673 and 4,018,576. The advantages of this composition manifested themselves in a dental tool manufactured by Abrasive Technologies, Inc., presently of Lewis Center, Ohio, and sold under the trademark TWO STRIPER™. The improvements incorporated into this new product spurred competition, resulting in improvements in electroplated diamond rotary instruments worldwide.
Throughout the industry, the principal attributes for diamond bonded dental tools are generally considered to be cutting speed and durability. In an attempt to sidestep the issue of durability, some manufacturers began to provide a “disposable” dental tool having an initial fast cutting speed with a competitive cost-per-use basis and the convenience of disposability. However, many early disposable tools were of inferior quality and exhibited accelerated dulling. Accordingly, the migration toward disposable diamond dental tools was initially slow to catch on, but has gained in popularity over the recent past.
Among the prior art products, the traditional offering was multiple choices of grit size to provide various tool characteristics. Coarse grit, typically in the range of 100-140 mesh was offered for rapid cutting, while fine grit in the range of 230-325 mesh was available for those practitioners who wanted to give a dental surface a finer finish in a second step. As diamond dental tools developed, in the 1980's and 1990's manufacturers began to boast of more diamond grit coverage on the cutting surface of the tools, many attempting to reach 100% concentration with coarser grits of up to 60 grit and improved diamond bonding. The emphasis on speed of cut and maintenance of the speed of cut after the first usage became the de facto standard by which dental tools were measured. This prompted a renewed interest in disposable tools, which had by this time improved in quality to the point they were seriously being considered as viable alternatives to the multiple-use tools.
To further increase cutting and durability performance in the tools of the prior art, manufacturers began to employ such methods as interrupting the dense, often approaching 100%, diamond grit surface area coverage. Examples of interrupted patterns included diamonds bonded in spiral or cross hatched patterns on the tool blank. This interruption in the gritted surface has the effect of forcing the leading grit crystals following the interruption to cut more effectively, even when they have dulled. Such a variety of a tool, also sold under the trademark TWO STRIPER™ TS2000 by Abrasive Technology, included a spiral pattern to compete with the ever growing popularity of coarser and, presumably, faster cutting tools. However, the use of a coarser grit on a diamond dental tool drives a need for a user to change tools in order to finish the work with a finer grit tool, thus requiring a separate, second step.
Even with the aforementioned improvements in initial cutting speed and durability, rotary diamond dental tools still suffer from a marked deterioration in cutting speed after multiple uses. What is needed is a dental tool that provides fast cutting using a finer grit, is durable and can reduce the overall amount of time the tooth is subjected to the abrasive actions of the tool. A dental tool that can be used for both cutting and finishing of dental material is also needed.